There are currently numerous non-invasive imaging techniques that can be used to produce images of a given object. Such techniques include X-rays, magnetic resonance imaging (“MRI”), computed tomography (“CT” or “microtomography”) scans, ultrasound and optical imaging using structured light, among others. In addition, various non-invasive optical imaging techniques such as bioluminescence and fluorescence can be used to produce optical images of animal objects, such as in the areas of medical research, pathology, drug discovery and development, and the like. Each such imaging technique has advantages and disadvantages that are useful for different imaging applications. Some techniques are well suited to provide spatial or anatomical information for internal parts, while others are more suited to provide functional information for an activity of interest within an object being imaged. Due to the differing advantages of different types of imaging systems, it has become increasingly desirable to combine the outputs and strengths of multiple imaging systems for a single imaging object.
As one particular example of a multi-modal imaging system, there can be a considerable synergistic advantage to combining x-ray microtomography (also known as computed tomography or CT) imaging and optical tomography to increase the information content of the optical measurements of a given imaging object. In particular, the morphological information obtained by microtomography provides anatomical information that assists the interpretation of the optical data and improves the model for light transport that is required to reconstruct the light source distribution.
Performing optical diffuse tomography reconstruction generally requires a measurement of the surface topography of a three-dimensional imaging object. Previous systems to accomplish such reconstructions have utilized an optical structured light technique to scan the surface of the imaging object and produce a surface mesh. This method often works well, but is limited by complexities like rough fur or dark colors on a given imaging object. Furthermore, the structured light typically only gives the surface topography on the top half of the imaging object. Thus, there can be several inherent drawbacks to some multi-modal imaging systems, at least with respect to those that use structured light as one of the imaging modes.
Furthermore, a single imaging object is often transferred between different imaging systems in many traditional multi-modal imaging systems, such as a combination of x-ray and optical systems. As might be expected, however, the transfer of an imaging object can result in various problems with coordinating the different object images. Imaging object transfer issues can include, for example, jostling or bumping by the person or apparatus moving the object between disparate imaging systems. Further problems can arise where the imaging object is a living animal or specimen, such as a mouse, that would ordinarily be inclined to move on its own during the transfer. Substantial changes in imaging object positioning, muscle flexing and the like during a transfer between imaging systems can then result in images from the second and/or subsequent imaging systems that do not overlap well with images from the first and/or prior imaging systems. Efforts to combine such disparate systems into a single imaging system are quite difficult, due to the different requirements, mechanisms and other items that tend to interfere with each other.
While many systems and methods for providing multiple types of images of a object have generally worked well in the past, there is always a desire to provide new and improved ways to obtain such internal images. In particular, what is desired are systems and methods that can produce multiple types of images of an imaging object without any need to transfer the object between separate imaging systems.